In the past, shoe manufacture began as a purely craft-oriented activity and, over time, has evolved to reach current industrialisation figures. One of the components of shoes where industrial progress has been greatest is the shoe sole, which is frequently produced by moulding. Examples of manufacturing footwear outsoles in moulds may be found, inter alia, in Spanish Patents Nos. 534,346, 534,783 and 2,007,466. However, there is a general tendency to manufacture shoes following the most conventional and craft-oriented method as far as the production of soles is concerned, since manual assembly of the different components gives the shoe characteristics of comfort and flexibility, which is unusual in the industrial processes used nowadays. In fact, it should be stated that the craft-oriented production of shoes has virtually died out.
On the other hand, recent times have seen a strong ecological/naturist trend in society and increasing concern about "synthetic" waste products which cannot be absorbed naturally, with a search for substitutes for these in the form of biodegradable-type materials.
In the field mentioned above, the Applicant has directed its research work towards the production of shoes using more "natural" raw materials, not forgetting the guarantees and performance levels contributed by new technologies, to which end use is made of naturally tanned skins, such as hand-oiled American pull or oiled flesh split, noble metals such as brass for eyelet holes, leather lining, leather middle soles, etc. Logically, synthetic materials, such as EVA or synthetic counters, affording greater reliability in terms of strength, solidity and comfortable fit of the shoe, are combined with these materials.
Likewise, the Applicant provides the major innovation of using used tires for producing the outer sole of the shoes, so continuing old attempts such as described in French Patents Nos. 935,251, 967,459 and 1,016,956, but essentially improving them in respect of the technology which has been developed in order to obtain better results than before.